Totem and Taboo of 1913 goes much further than the later essay. Freud takes the anthropology available to him, chiefly the evolutionary schemes of Frazer, Robertson Smith and Darwin's speculation about a primal horde, and constructs an origin event: a band ruled by a violent father who monopolised the women, a rebellion in which the sons killed and ate him, and a guilt so unbearable that it produced, in one stroke, the totem meal, the prohibition of incest, and the first god. Every later religion, he argues, is a repetition of that crime and that remorse.
Almost nothing in that reconstruction survived professional scrutiny. The evolutionary anthropology it depends on was already being abandoned; the primal horde is not attested anywhere; and the argument requires an inherited memory of an actual event passed down the generations, a Lamarckian mechanism Freud held to for the rest of his life and which biology does not permit.
Moses and Monotheism, published in 1939, applies the same method to a specific case. Moses, Freud argues, was an Egyptian, a follower of the suppressed religion of Akhenaten who carried its monotheism to a Semitic people, was murdered by them, and became the object of a returning repressed guilt that shaped Judaism. No Egyptologist and no biblical scholar has accepted it. The atlas records the thesis because it is historically significant and because it is still widely repeated, and records that it is not held by the fields that would have to hold it.